Printing device in a recording calculator or the like

ABSTRACT

The platen of a printing device in a recording calculator can be moved into and out of printing position by engaging and disengaging an actuating linkage with and from a driving mechanism by means of a control device, whereby printing is selectively carried out or not carried out. This movement of the platen is utilized also to rotate the platen and advance the recording sheet through relatively large increments of advance to improve legibility of printed numerals and facilitate detection of errors.

United States Patent Inventors Rli Watanabe Tagata-gun, Shlzuolra-ken; Talrlslll Murakami, Mishima-shi; Kiyolrazu Kohoyuhi, Tagata-gun, Shlzuolta-lren, all of Japan 735,244

June 7, 1968 Nov. 2, 1971 Tokyo Denki Klblllhlkl Keisha Tokyo-to, Japan Appl. No. Filed Patented Assignee PRINTING DEVICE IN A RECORDING CALCULATOR OR THE LIKE 5 Claims, 5 Drawing Figs.

US. Cl. 235/58 P, 101/93 R Int.

Field oISeareh 235/58 P,

[56.] References Cited UNITED STATES PATENTS 1,812,161 6/1931 Mapel zss/sox 2,682,994 7/1954 Boyden et a1. 235/6025 3,321,133 5/1967 Okuda 235/60 3,358,918 12/1967 Gassino et a1 235/6051 FOREIGN PATENTS 1,263,358 1968 Germany 235/6025 Primary Examiner- Richard B. Wilkinson Assistant Examiner-John F. Gonzales Attorneys Robert E. Burns and Emmanuel]. Lobato ABSTRACT: The platen of a printing device in a recording calculator can be moved into and out of printing position by engaging and disengaging an actuating linkage with and from a driving mechanism by means of a control device, whereby printing is selectively carried out or not carried out. This movement of the platen is utilized also to rotate the platen and advance the recording sheet through relatively large increments of advance to improve legibility of printed numerals and facilitate detection of errors.

PRINTING DEVICE IN A RECORDING CALCULATOR OR THE LIKE BACKGROUND OF THE INVENTION This invention relates generally to the fields of recording calculators and the like and of printing devices. More particularly, the invention concerns a new and improved printing device in a recording calculator or the like which device has a mechanism for changing over the printing mechanism between printing and not printing in operations such as multiplication and division and a device for feeding and advancing recording paper.

lleretofore, in an electrically operated recording calculator provided with a conventional printing device of platen-striking type, it has been extremely difficult to operate the calculator in a nonprinting state, whereby unnecessary numerical values were unavoidably printed even in the calculation step following the printing oftlte multiplier or divisor in multiplication or division.

In a recording calculator, it is necessary to feed the recording paper at each instance of printing a calculation value. In most devices known heretofore for this purpose, a ratchet wheel in each case is provided on a platen roll, on which the printing is accomplished, and a lever for rotating the ratchet wheel by an incremental angle correspond to one tooth thereof and a roller for stopping and holding the ratchet wheel are provided and adapted to operate cooperatively with the platen roll to feed the recording paper in the desired manner. These mechanisms known heretofore, however, have been complicated. Moreover, since the printed recording paper in a known device of this type is shifted by singly spaced lines corresponding to one tooth of the ratchet wheel, it is difficult to read the printed numbers.

SUMMARY OF THE INVENTION The present invention, in a broad aspect thereof, contemplates eliminating the above described disadvantageous features in recording calculators.

It is a first object of the present invention to provide a printing device in a recording calculator or the like in which device an actuating linkage for moving a platen roll into and out of printing position is engageable with and disengageable from a driving mechanism, whereby, even in the case of a printing mechanism of platen-striking type, the device can be readily changed over between printing and not-printing states, and unnecessary printing can be eliminated.

A second object of the invention is to provide a printing device in a recording calculator or the like which device is an extremely simple mechanism comprising a ratchet wheel fixed to the platen roll shaft and a ratchet actuating and holding device, which mechanism is operated by the movements of the platen roll into and out of printing position to advance the recording paper, at each instance of retraction of the platen roll, by an incremental distance which is substantially greater than that heretofore attainable, whereby the legibility of the printed numerals is improved, and errors in setting numbers can be readily discovered.

The nature, principle, details, and utility of the invention will become more clearly apparent from the following detailed description with respect to a preferred embodiment of the invention when read in conjunction with the accompanying drawings, in which likeparts are designated by like reference numerals and characters.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view, with parts cut away and with some parts in exploded state, showing the essential parts of an example of the printing device according to the invention for changing over between printing and not printing;

FIG. 2 is an elevational axial view showing a main shaft and some related parts of the device shown in FIG. 1 as viewed from the left toward the right;

FIG. 3 is a fragmentary perspective view showing an essential shifting mechanism of the device shown in FIG. 1 in a notprinting state;

FIG. 4 is a partly fragmentary perspective view showing one example of a device according to the invention for advancing recording paper; and

FIG. 5 is an elevational view, as viewed from the left, of the d device shown in FIG. 4.

For consistency in designating directions, terms such as left," right," front," and "rear" and related terms herein used are in conformance with the indication at the lower righthand part of FIG. 1. That is, the part of the device nearest the operator, who would normally face the device from the right foreground in FIG. 1, is the front part, and the part to the left of the operator is the left part. All rotational directions are those as viewed from the left side toward the right side.

DETAILED DESCRIPTION Referring first to FIGS. 1, 2, and 3,11 fixed shaft 1 extending horizontally in the left-right direction pivotally supports the lower parts of a pair of parallel support plates 2 and In, between which and by the upper parts of which the shaft 4 of a platen roll 3 is rotatably supported. The support plates 2 and 2a are provided in their upper parts with pins 6 and 6a respectively extending leftward and rightward and rotatably engaged with the front ends of links 5 and 50 disposed parallelly in vertical front-to-rear planes and having horizontal stud shaft 7 and 7a fixed to their rear parts. Tension springs 8 and 8a are respectively connected to the rear ends of the links 5 and 5a to impart rearward forces thereto.

Below the links 5 and 5a and to the rear of the support plates 2 and 2a, there is provided a stationary shaft 10 extending horizontally in the left-right direction. A sleevelike hollow shaft 11 is fitted around this shaft 10 and is free to rotate therearound and slide therealong. A pair of actuating levers l2 and 120, are parallelly fixed st their middle parts to the hollow shaft 11 and are angularly tilted so that one end of each lever is higher then the other. The upper ends of these levers l2 and are respectively provided with through holes 13 and 13a in which the above mentioned shafts 7 and 7c are fitted slidably in the left-right direction. The outer ends of the shafts 7 and 7a are provided with stops I4 and 14a fixed thereto.

A main rotary shaft 15 is rotatably supported in a horizontal position forward and below the above mentioned stationary shaft 10 and supports rotating plates 16, 16a and 17 fixed thereto. The shaft 15 is driven by an electric motor not shown. The rotating plates 16 and 16a respectively have rollers 18 and 18a rotatably supported on the side surfaces of the rotating plates and adapted to engage the lower ends of the above mentioned actuating levers l2 and 12a. The main shaft 15 is coupled to a printing driving mechanism (not shown).

Vertically between and to the rear of the shafts l0 and 15, there is provided a second shaft 20 extending in the left-right direction and supporting a hollow shaft 21 which is fitted therearound and is free to rotate and slide axially relative thereto. An L-shaped lever 22 is fixed at its bend to the hollow shaft 21 and has a recess in the lower edge of one of its arms, which recess is engageable with a roller 23 rotatably supported on the side of the above mentioned rotating plate 17 as shown in FIG. 2.

A short sleeve or collar 25 is fitted on the left end part of the shaft 20, and a compression coil spring 26 is disposed around the shaft 20 to the right of the hollow shaft 21 to impart a leftward spring force to the hollow shaft 21. The collar 25 supports an upwardly extending rod 27 imbeddedly fixed thereto at its lower end and projecting upward through a slot 29 formed in the left-right direction in the horizontal lower flange of a stationary bracket 28 having a vertical web part and a horizontal upper flange.

The upper end of the rod 27 is engaged with an edge 32a diagonally inclined in the horizontal plane of a plate 32 connected to the rear part of a slide bar 31 disposed in the frontrear direction and supported at its middle part by a support pin 30 supported by a stationary frame part not shown so that it can slide in the front-rear direction. The front end of the slide bar 31 is joined by a pin 35 to the upper end of a lever 34 pivotally supported at its middle part on a stationary shaft 33. The lower end of this lever 34 is in abutting engagement with the tip of the upper arm of another level 37 pivotally supported at its middle part on a stationary shaft 36. The lower arm of this lever 37 is pulled forward by a tension spring 38, whereby the upper arm of this lever is urged rearward.

The outer end part of the upper arm of the lever 37 is bent rearward and has at its lower edge a latch 39 engageable with an engagement lug 42 formed at an intermediate part of a lever 41 extending approximately in the front-rear direction and pivotally supported at its rear end by a stationary shaft 40. This lever 41 is provided at its front end with a downwardly operable push button 44 and is urged upward against the upper arm of the lever 37 by a tension spring 43, whereby the latch 39 is engaged by the engagement lug 42, and the upper arm of the lever 37 is thereby locked against rearward movement when the button 44 is in the normal undepressed state. The lower end of the lever 37 is coupled by a link 45 to a mu]- tiplication and division mechanism (not shown).

A collar 50 is fitted on the left part of the aforementioned shaft to abut against the left end of the hollow shaft 11 and is urged rightward by a compression coil spring 51 disposed around the left end part of the shaft 10. A vertical rod 57 is fixed at its lower end to the collar 50 and extends upwardly through and past a slot 52 formed in the left-right direction in the upper horizontal flange of the aforementioned stationary bracket 28 and a zigzag diagonal slot 56 formed in a horizontal slide late 53 to overlap the slot 52. The slide plate 53 is slidably supported on the upper surface of the upper flange of the bracket 28 and can slide in the front-rear direction, guided and limited in movement by pins 55, 55 fixed to the upper flange of the bracket and engaged respectively with slots 54, 54 formed in the front-rear direction in the slide plate 53. The rear part of the slide plate 53 is bent downward to form a flange in a position to engage the upwardly extending arm of the aforementioned L-shaped lever 22.

In front of and to the left of the slide plate 53, there are provided levers 6i and 62 respectively pivoted at their upper and front ends on a stationary shaft 60 and having respective distal ends directed downward and rearward. The upper part of the lever 61 and the front part of the lever 62 are coupled through a spring 63. The lower part b of the lever 61 is engaged with the front edge b of the aforementioned plate 32 of the slide bar 31 as shown in FIG. 3, and a rear bent flange c of the lever 62 is engageable with a stepped shoulder 0 provided on the left edge of the slide plate 53.

The device according to the invention of the above described organization operates in the following manner. In the state of the device for ordinary printing, hollow shaft 11 is in its leftward position, and actuating levers 12 and 12a are in their positions for engagement with rollers 18 and 18a. Accordingly, when main shaft rotates in the arrow direction shown in FIG. 1, rollers 18 and 18a engage with levers 12 and 12a, which thereby rotate clockwise as viewed from the left and move links 5 and 5a forward through stud shafts 7 and 7a. Therefore, support plates 2 and 2a and platen roll 3 are moved forward for printing by printing types on a printing wheel 75 (as shown in FIGS. 4 and 5) on recording paper 82 on platen roll 3.

ln operations such as multiplication or division, for example, button 44 is manually depressed after the multiplier or divisor has been set, whereupon lever 41 is moved downward, and its engagement lug 42 disengages from latch 39. Consequently, lever 37 is released and is rotated counterclockwisely by the force of spring 38, causing lever 34 to rotate clockwisely, whereby slide bar 31 is pulled forward, and the inclined edge 32a of plate 32 forces rod 27 rightward. Accordingly, collar 25, hollow shaft 21, and lever 22 are shifted rightward, sliding on stationary shaft 20, and lever 22 is thus placed in position for engagement by roller 23 on rotating plate 17.

On one hand, the front edge b, of plate 32 pushes forward the lower part b, of lever 61, which thereby rotates counterclockwisely and tensions spring 63, whereby flange c of lever 62 is pressed against slide plate 53.

Then, when main shaft 15 rotates in the arrow direction, platen roll 3 is moved forward similarly as in the preceding case of ordinary printing, and the multiplier or divisor is printed. Thereafter, when main shaft 15 rotates in the same direction, roller 23 on rotating plate 17 engages the lower part of lever 22, which thereby rotates in the counterclockwise direction and moves slide plate 53 rearward. Consequently, inclined slot 56 in plate 53 forces rod 57 toward the left, thereby moving collar 50, hollow shaft 11, and actuating levers 12 and 12a also toward the left, levers 12 and 12a thereby being placed in positions where they cannot be engaged by rollers 18 and 184.

On one hand, when slide plate 53 reaches its rearmost position, flange c, of lever 62 drops into engagement with shoulder Cg of plate 53, and the device is locked in this state thus attained. Accordingly, no printing occurs in the succeeding calculation process step even when shaft 15 rotates.

When the above mentioned calculation has been completed, the multiplication or division mechanism sued therefor (not shown) actuates link 45 rearward, whereby the above described operation is carried out in reverse order, and the device returns to its original state wherein printing can be accomplished.

in one example, as illustrated in FIGS. 4 and 5 of a recording paper feeding mechanism according to the invention, a ratchet wheel 70 is fixed to projecting end of the shaft 4 of the platen roll 3. A stop pin 72 engageable with the vertical front edge of a side plate 71 is fixed to the upper rear part of the support plate 2. A knob 73 for manually rotating the platen roll 3 is fixed to the other end of the platen roll shaft 4. A roll 74 of recording paper 82 to be fed to the platen roll 3 is rotatably supported at one end on the side plate 71. In front of and at a level slightly below the platen roll 3, there is provided a printing wheel 75 fixed to and supported by a shaft 76 parallel to the platen roll 3, and an ink ribbon 77 is supported between the printing wheel 75 and the platen roll 3.

The above mentioned ratchet wheel 70 is engaged at its lower part by a detent pin fixed to the front end of an engagement lever 79 pivoted at its rear end on pivot shaft 78 and urged upward with suitable force toward the ratchet wheel 70 by a tension spring 81.

The support plates 2 and 2a and the platen roll 3 are tilted and returned into and out of the printing position about the shaft 1 by the same device and in the same manner as described hereinbefore in conjunction with H05. 1, 2, and 3.

The paper feeding mechanism of the above described organization according to the invention operates in the following manner. When main shaft 15 rotates in the arrow direction in FIG. 4, rollers 18 and 18a on rotating plates 16 and 16a strike against actuating levers l2 and 12a, which thereby rotate clockwisely to move forward links 5 and 5a, whereby support plates 2 and 2a are tilted clockwisely to move platen roll 3 forward toward printing wheel 75.

At the same time, since detent pin 80 is being pressed by spring 81 against the lower side of ratchet wheel 70 on the same shaft 4 as platen roll 3, ratchet wheel 70 and platen roll 3 are turned in the clockwise direction. Consequently, recording paper 82 wrapped around platen roll 3 is returned in the direction reverse to the feeding direction, whereby the print ing line position d, is shifted in this instance to a printing position d and a numeral of printing wheel 75 is imprinted on the part of paper 82 at this position (1,.

When, after this printing operation, rotating plates 16 and 16a rotate further, and rollers 18 and 18a disengage from the lower ends of actuating levers l2 and 12a, links 5 and 5a are pulled rearward by the force of springs 8 and 80, whereby support plates 2 and 2a and platen roller 3 are retracted rearwardly. At the same time, the lower side of ratchet wheel 70 engages with detent pin 80, whereby platen roll 3 is rotated in the counterclockwise direction, and paper 82 is moved in the feeding direction.

In this instance, however, platen roll 3 is caused to rotate with greater angular momentum than in the preceding instance, whereby ratchet wheel 70 forces detent pin 80 downward, overcoming the force of spring 81 and thereby rotating further through an angle corresponding to an additional ratchet tooth. Consequently, the printing position d of paper 82 is moved to the preceding printing position d In this manner, the recording paper is successively printed and moved through the printing mechanism.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the d'nclosure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

What we claim is:

1. In a recording calculator or the like, a printing device comprising, in combination: a printing type mechanism including ink supply means; a platen roll for holding recording paper for printing thereon by said type mechanism and for moving said paper to shift the printing line thereof, said platen roll having a central shaft; a movable support structure rotatably supporting the platen roll and adapted to undergo advancing and retracting movements whereby the platen roll is moved into and out of printing position relative to the type mechanism; a main rotary shaft; a rotary plate attached to said main rotary shaft and having a roller fixed thereto; an actuating linkage engageable with and operable by said roller on rotation of said main rotary with and operable by said roller on rotation of said main rotary shaft, said linkage being provided with a resilient means adapted to restore said linkage upon disengagement of said linkage from said roller, thereby to actuate said movable support structure through said advancing and retracting movements; means for moving said linkage axially of said main rotary shaft for establishing and breaking engagement between said linkage and said roller; a toothed wheel coaxially fixed to said shaft of the platen roll; and platen rotating and holding means engaging and operating cooperatively with said toothed wheel to rotate the platen roll slightly in reverse direction during said advancing movement and to rotate the platen roll in forward direction through a relatively large angle during said retracting movement thereby to advance said paper.

2. In a recording calculator or the like, a printing device comprising, in combination: a printing type mechanism including ink supply means; a platen roll for holding a recording sheet for printing thereon by said type mechanism and for moving said sheet to shift the printing line thereof; a movable support structure rotatably supporting said platen roll and adapted to undergo movements whereby the platen roll is moved into and out of printing position relative to the type mechanism; a main rotary shaft; at least one rotary plate attached to said shaft and having a roller fixed thereto; and an actuating linkage engageable with and operable by said roller upon rotation of said main rotary shaft, said linkage being provided with a resilient means adapted to restore said linkage upon disengagement of said linkage from said roller, thereby to actuate said movable support structure through said movements; and means for moving said linkage axially of said main rotary shaft for establishing and breaking engagement between said linkage and said roller.

3. A printing device in a recording calculator or the like according to claim 2, wherein said actuating linkage comprises a stationary shaft, a sleevelike hollow shaft fitted around said stationary shaft, a pair of actuating levers each engageable with said roller parallelly fixed to said hollow shaft and linked to said movable support structure, and spring means biasin sald hoilow shaft axially on said stationary shaft to shift said actuating levers to the engageable position in normal condition, and said control device comprising a slide plate having an inclined slot, a vertical rod fixed to a collar fitted on the end of said hollow shaft and engaged in said inclined slot, and means to shift said slide plate in opposition to said spring means from a position in which said actuating levers are engageable with said rollers to another in which said levers are not engageable with said rollers.

4. A printing device in a recording calculator or the like, as claimed in claim 3, further comprising a toothed wheel coaxially fixed to said platen roll, and platen rotating and holding means comprising an engagement lever operable by said actuating linkage and having a pin engageable with said toothed wheel, said engagement lever being elastically biased to hold said pin engaged with said toothed wheel in nonnal condition to lock rotation of said toothed wheel and said engagement lever being disposed so that said pin rotates said toothed wheel forwardly upon forward actuation of said actuating linkage and said pin moves freely and rearwardly over a tooth of said toothed wheel upon restoration of said linkage; and said platen rotating and holding means engaging and operating cooperatively with said toothed wheel to rotate the platen roll slightly in a reverse direction during said advancing movement and to rotate the platen roll in a forward direction through a relatively large angle during said retracting movement thereby to advance said paper.

5. A printing device in a recording calculator or the like according to claim 2, wherein said actuating linkage comprises a first shaft, a sleevelike hollow shaft fitted around said first shaft, a pair of actuating levers engageable with said main rotary shaft parallelly fixed to said hollow shaft and linked to said movable support structure, and spring means biasing said hollow shaft on said stationary shaft to shift said actuating levers to the engageable position in normal condition, and said control device comprising a slide plate having an inclined slot, a vertical rod fixed at its lower end to a collar fitted on the end of said hollow shaft and extending upwardly through and past said slot, a second shaft extending in parallel with said first shaft, an L-shaped lever mounted around the second shaft so as to be slidable along the axis of said second shaft and engageable with said main rotary shaft and said slide plate so that said second shaft shifts said actuating levers from the position in which said levers are engaged with said rollers to a position of out of engagement, means to hold said slide plate in the shifted position, means to displace said L-shaped lever to the engageable position, means movable corresponding to a multiplication or division operation and being engaged with said means for holding said slide plate, and a manual control member locking said last-mentioned means in normal condition and releasing said last-mentioned means when said member is operated. 

1. In a recording calculator or the like, a printing device comprising, in combination: a printing type mechanism including ink supply means; a platen roll for holding recording paper for printing thereon by said type mechanism and for moving said paper to shift the printing line thereof, said platen roll having a central shaft; a movable support structure rotatably supporting the platen roll and adapted to undergo advancing and retracting movements whereby the platen roll is moved into and out of printing position relative to the type mechanism; a main rotary shaft; a rotary plate attached to said main rotary shaft and having a roller fixed thereto; an actuating linkage engageable with and operable by said roller on rotatIon of said main rotary with and operable by said roller on rotation of said main rotary shaft, said linkage being provided with a resilient means adapted to restore said linkage upon disengagement of said linkage from said roller, thereby to actuate said movable support structure through said advancing and retracting movements; means for moving said linkage axially of said main rotary shaft for establishing and breaking engagement between said linkage and said roller; a toothed wheel coaxially fixed to said shaft of the platen roll; and platen rotating and holding means engaging and operating cooperatively with said toothed wheel to rotate the platen roll slightly in reverse direction during said advancing movement and to rotate the platen roll in forward direction through a relatively large angle during said retracting movement thereby to advance said paper.
 2. In a recording calculator or the like, a printing device comprising, in combination: a printing type mechanism including ink supply means; a platen roll for holding a recording sheet for printing thereon by said type mechanism and for moving said sheet to shift the printing line thereof; a movable support structure rotatably supporting said platen roll and adapted to undergo movements whereby the platen roll is moved into and out of printing position relative to the type mechanism; a main rotary shaft; at least one rotary plate attached to said shaft and having a roller fixed thereto; and an actuating linkage engageable with and operable by said roller upon rotation of said main rotary shaft, said linkage being provided with a resilient means adapted to restore said linkage upon disengagement of said linkage from said roller, thereby to actuate said movable support structure through said movements; and means for moving said linkage axially of said main rotary shaft for establishing and breaking engagement between said linkage and said roller.
 3. A printing device in a recording calculator or the like according to claim 2, wherein said actuating linkage comprises a stationary shaft, a sleevelike hollow shaft fitted around said stationary shaft, a pair of actuating levers each engageable with said roller parallelly fixed to said hollow shaft and linked to said movable support structure, and spring means biasing said hollow shaft axially on said stationary shaft to shift said actuating levers to the engageable position in normal condition, and said control device comprising a slide plate having an inclined slot, a vertical rod fixed to a collar fitted on the end of said hollow shaft and engaged in said inclined slot, and means to shift said slide plate in opposition to said spring means from a position in which said actuating levers are engageable with said rollers to another in which said levers are not engageable with said rollers.
 4. A printing device in a recording calculator or the like, as claimed in claim 3, further comprising a toothed wheel coaxially fixed to said platen roll, and platen rotating and holding means comprising an engagement lever operable by said actuating linkage and having a pin engageable with said toothed wheel, said engagement lever being elastically biased to hold said pin engaged with said toothed wheel in normal condition to lock rotation of said toothed wheel and said engagement lever being disposed so that said pin rotates said toothed wheel forwardly upon forward actuation of said actuating linkage and said pin moves freely and rearwardly over a tooth of said toothed wheel upon restoration of said linkage; and said platen rotating and holding means engaging and operating cooperatively with said toothed wheel to rotate the platen roll slightly in a reverse direction during said advancing movement and to rotate the platen roll in a forward direction through a relatively large angle during said retracting movement thereby to advance said paper.
 5. A printing device in a recording calculator or the like according to claim 2, wherein said actuating linkage comprises a fiRst shaft, a sleevelike hollow shaft fitted around said first shaft, a pair of actuating levers engageable with said main rotary shaft parallelly fixed to said hollow shaft and linked to said movable support structure, and spring means biasing said hollow shaft on said stationary shaft to shift said actuating levers to the engageable position in normal condition, and said control device comprising a slide plate having an inclined slot, a vertical rod fixed at its lower end to a collar fitted on the end of said hollow shaft and extending upwardly through and past said slot, a second shaft extending in parallel with said first shaft, an L-shaped lever mounted around the second shaft so as to be slidable along the axis of said second shaft and engageable with said main rotary shaft and said slide plate so that said second shaft shifts said actuating levers from the position in which said levers are engaged with said rollers to a position of out of engagement, means to hold said slide plate in the shifted position, means to displace said L-shaped lever to the engageable position, means movable corresponding to a multiplication or division operation and being engaged with said means for holding said slide plate, and a manual control member locking said last-mentioned means in normal condition and releasing said last-mentioned means when said member is operated. 